Katy Perry has announced details of her new album, using a giant golden lorry. The album's title – Prism – and its release date – 22 October – were revealed on the side of a semi-trailer truck, spotted on the streets of Los Angeles.

News of the Prism lorry first came from fans, who shared their snaps on Facebook and Instagram. "Find the #PRISM semi, take a picture and I'll RT you," Katy Perry later tweeted. "Don't worry, Los Angeles is just the first stop on the map." She kept her word, sending one-liners to lucky tweeters, and confirming that Prism is her fourth LP, not just a single.

A prism's rainbow palette certainly seems apt for Perry's pop aesthetic. But it's also an odd title for a record released in 2013 when whistleblower Edward Snowden revealed the NSA's Prism surveillance programme less than two months ago.

But then, focusing her attentions on a major political issue could be an apt choice for the 28-year-old, who has been vocal in her support for gay rights, universal healthcare, and the need for "a revolutionary change" in US society.

Perry's first album in three years has a lot to live up to. In 2008, One of the Boys received a platinum sales certificate both at home and in the UK, while 2010's Teenage Dream did even better, selling more than 6m copies worldwide. All but one of her last eight singles reached the UK top 10, and all but two made No 1 in the US.